JP2000121358A - Method and device for obtaining inspection point position - Google Patents

Abstract

PROBLEM TO BE SOLVED: To find the position of an arbitrary point in an inspection area included in the plane of a structure to be inspected on the plane. SOLUTION: An actual size coordinate system is set by installing four indexes on the plane structure 4. Two kinds of wide-area and narrow-area digital images of the plane structure are obtained by a camera 1 and a film reader 2. A data process part 3 calculates a first projection conversion coefficient from the pixel coordinates and actual size coordinates of the four indexes in the wide-area image. A second projection conversion coefficient is calculated on the basis of coordinate information on two corresponding places in the narrow-area and wide-area images. For the narrow-area image, an arbitrary point to be inspected is inputted and coordinate conversion is performed by using the first projection conversion coefficient and second projection conversion coefficient.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for determining a position of an arbitrary point in an inspection area included in a plane of a structure to be inspected.

[0002]

2. Description of the Related Art In the maintenance and inspection of a long and long planar structure (typically, a concrete wall or the like), appearance is generally an important quality judgment factor. For example, the length, width, presence or absence of water leakage, and the like of a crack can be read from the appearance of the structure.
In recent years, a method has been developed in which a photograph of an external appearance image of a planar structure is taken and then inspected by performing digital image processing and analysis measurement with a computer. By using this method, the inspection can be performed remotely while looking at the display screen.

In such an inspection method based on computer analysis, the resolution at the time of A / D conversion of an image is important. For example, in order to detect a small crack having a width of about 0.1 mm, a resolution of about 0.025 mm is required as a distance between pixels on a digital image.

[0004] At this time, a problem is the size of the digital image. For example, if it is intended to cover 50 cm × 50 cm with the above resolution, the number of pixels of 20000 × 20000 is required alone. If this image is stored at a gradation of 8 bits per pixel, a storage capacity of about 400 MByte is required. Therefore, when storing the entire planar structure having a size on the order of several meters to several tens of meters at this resolution and gradation,
A gigabyte order memory is required. In addition, a computer that executes image processing also requires high processing capability. For these reasons, conventionally, the presence of a point requiring inspection has been confirmed from the appearance of the structure, and only the image of that location has been captured with high resolution and computer image analysis has been performed.

[0005]

As described above, the conventional image analysis of a crack is suitable for analyzing the crack itself because the image of the crack is obtained at a high resolution. The position of the structure to be inspected may be a problem.

[0006] For example, when a thing that looks like a crack is found in a dam, depending on its position, it is necessary to actually climb the dam wall on the site and conduct a detailed investigation of that part. However, since such a detailed survey requires an enormous amount of time and effort, there has been a demand to confirm the position of the crack on the dam wall in advance.

In response to this demand, if only a rough position acquisition is performed, a person can look at the entire dam and find the position of the cracked portion. For this purpose, it is ideal to take a picture of the dam from the front and obtain a facing image.However, such a shooting is not easy from the viewpoint of securing a shooting place, and usually the shooting is performed from an oblique angle, so the photograph is taken. It was difficult to see the location of the crack.

The present invention has been made in view of the above-mentioned conventional problems, and provides an inspection point position obtaining method and apparatus for obtaining a position on an arbitrary plane of an inspection area included in a plane of an inspection target structure. The purpose is to do.

[0009]

An inspection point position obtaining method according to the present invention is an inspection point position obtaining method for obtaining an arbitrary point of an inspection area included in a plane of a structure to be inspected on the plane. Reading an inspection image in which the inspection area is imaged, reading a plane image in which the inspection area is imaged with a plurality of reference points determined in advance on the plane, and reading the plurality of reference points measured in advance. Setting the position data, and recognizing the coordinates of the plurality of reference points in the plane image, and, based on the recognized coordinates and the set position data, changing any coordinates of the plane image to the plane. Calculating a coefficient for converting to a position in the inspection image, and based on a plurality of common imaging points common to the inspection image and the planar image, arbitrary coordinates of the inspection image Calculating a coefficient for converting to the coordinates of the plane image, and when an arbitrary point is specified in the range of the inspection image, the coordinates of the inspection image at the specified arbitrary point are calculated as the coordinates of the plane image. Using a coefficient for converting to coordinates and a coefficient for converting to a position on the plane, converting to a position on the plane of the structure to be inspected.

[0010] An inspection point position acquisition method according to the present invention is an inspection point position acquisition method for finding the position on the plane of an arbitrary point in an inspection area included in the plane of a structure to be inspected,
Conventionally, the inspection area image for computer analysis is a partial image of a plane, so in addition to this image, an image of the entire plane is acquired stepwise while enlarging the imaging area, and coordinate conversion between these images is performed. It is intended to be associated with a coefficient.

First, an inspection image in which cracks and the like are captured is first read, and a planar image (whole image) in which a plurality of reference points and an inspection region determined in advance on a plane are captured is read. In addition, position data of a plurality of reference points measured in advance is set in a computer system or the like.

Next, the coordinates of a plurality of reference points specified by the operator on the plane image are recognized by a computer system or the like, and arbitrary coordinates of the plane image are determined based on the recognized coordinates and the set position data. Is calculated, ie, a coordinate conversion coefficient. This is a so-called projective transformation coefficient, which enables transformation including the following elements in the relationship between the plane image and the actual plane. That is, conversion with scaling, rotation, parallel movement, and inclination in the depth direction becomes possible.

Then, a computer system or the like performs an operation based on a plurality of common imaging points common to the inspection image and the plane image designated by the operator to convert arbitrary coordinates of the inspection image into coordinates of the plane image. Calculate the coefficient. This coefficient is also referred to as the "coefficient for converting to position".
Similarly to the above, they are projection transformation coefficients (coordinate transformation coefficients).

When the operator designates an arbitrary point whose position is desired to be obtained in the range of the inspection image, the coordinates of the inspection image at the specified arbitrary point are replaced with the arbitrary coordinates of the inspection image calculated in advance. Using a coefficient for converting to coordinates and a coefficient for converting arbitrary coordinates of a planar image to a position on a plane, coordinate conversion is performed stepwise to convert to a position on the plane of the inspection target structure. . Therefore, if an arbitrary point is designated as the inspection point in the range of the inspection image,
The position on the plane can be determined.

Further, the inspection point position acquiring device of the present invention is
An inspection point position acquisition device for determining a position on the plane of an arbitrary point of an inspection region included in a plane of an inspection target structure, wherein inspection image reading means for reading an inspection image obtained by imaging the inspection region, Plane image reading means for reading a plane image in which the plurality of reference points determined on the plane and the inspection region are imaged, reference point setting means for setting position data of the plurality of reference points measured in advance, and Recognizing the coordinates of the plurality of reference points in the plane image, and calculating a coefficient for converting any coordinates of the plane image to a position in the plane based on the recognized coordinates and the set position data. And converting the arbitrary coordinates of the inspection image into the coordinates of the plane image based on a plurality of common imaging points common to the inspection image and the plane image. A coordinate conversion coefficient calculating means for calculating the coefficients of the fit, when any point in the range of the test image is specified, the coordinates of the inspection image of the specified arbitrary point,
Using a coefficient for converting to the coordinates of the plane image and a coefficient for converting to a position on the plane, a conversion unit for converting the position of the inspection target structure into a plane,
The inspection point position obtaining apparatus according to the present invention is characterized by having the inspection point position obtaining method described above in order to obtain the position on the plane of an arbitrary point of the inspection area included in the plane of the inspection target structure. This is a embodied device that reads a plurality of images in which the imaging area is imaged stepwise to the entire plane and associates these images with a projective transformation coefficient (coordinate transformation coefficient), so that an arbitrary point in the range of the inspection image is obtained. To determine the position on the plane.

Each of the inspection image reading means and the plane image reading means comprises an A / D converter such as a film reader, and reads an inspection image and a plane image obtained by capturing a plurality of reference points and an inspection area.

Further, position data of a plurality of reference points measured in advance is inputted by an operator, and these are stored (set) in a memory by reference point setting means.

The position conversion coefficient calculating means recognizes the coordinates of a plurality of reference points specified by the operator on the plane image,
Based on the recognized coordinates and the set position data, a coefficient for converting arbitrary coordinates of the plane image into a position on the plane is calculated. This is a so-called projective transformation coefficient, which enables transformation including the following elements in the relationship between the plane image and the actual plane. That is, conversion with scaling, rotation, parallel movement, and inclination in the depth direction becomes possible.

When a plurality of common imaging points common to the inspection image and the plane image read by the inspection image reading unit and the plane image reading unit are input by the operator, the coordinate transformation coefficient calculating unit inputs the common imaging points. Based on the coordinates in each image, a coefficient for converting any coordinates of the inspection image into the coordinates of the planar image, that is, a projective conversion coefficient for coordinate conversion is calculated.

When the operator specifies an arbitrary point whose position is desired to be obtained within the range of the inspection image, the conversion means converts the coordinates of the specified arbitrary point in the inspection image into
Using a coefficient for converting any coordinates of the previously calculated inspection image into coordinates of the plane image and a coefficient for converting any coordinates of the plane image into a position on the plane, the coordinate conversion is performed step by step. Then, the position is converted into a position on the plane of the inspection target structure.

Further, the inspection point position acquisition device of the present invention
The plane image reading unit reads a plane image in which four reference points determined in advance to surround the inspection area are captured, and the reference point setting unit reads the four reference points measured in advance. Position data is set, and the position conversion coefficient calculation unit recognizes the coordinates of the four reference points in the plane image, and, based on the recognized coordinates and the set position data, calculates the position of the plane image. It is characterized in that a projective transformation coefficient consisting of eight coefficients for transforming an arbitrary coordinate into a position on the plane is calculated.

With this configuration, a projection transformation coefficient composed of eight coefficients can be calculated from four reference points defined so as to surround the inspection area. In the conversion to, conversion including elements of rotation, translation, scale, and inclination in the depth direction becomes possible.

Further, the inspection point position obtaining apparatus of the present invention
The coordinate transformation coefficient calculating means calculates a projective transformation coefficient composed of eight coefficients.

The coordinate conversion coefficient calculating means also calculates a projective conversion coefficient consisting of eight coefficients, so that in the conversion from the arbitrary coordinates of the inspection image to the coordinates of the plane image, rotation, translation, scale and inclination in the depth direction are performed. The conversion including the element of becomes possible.

Further, the inspection point position acquiring apparatus of the present invention
The coordinate transformation coefficient calculating means calculates the projective transformation coefficient by image processing using a non-linear optimization technique.

The projective transformation coefficient can be optimized by image processing using a non-linear optimization technique.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method and an apparatus for acquiring inspection point positions according to the present invention will be described below in detail with reference to FIGS.

FIG. 1 is a block diagram of a device configuration of a first embodiment of an inspection point position acquiring apparatus according to the present invention.

The camera 1 is an analog camera for photographing the appearance of a planar structure.

The film reader 2 is a device that scans and reads a photographic film and digitizes an appearance image of a planar structure.

The data processing unit 3 is a computer system that processes and analyzes the digital data of the appearance image to obtain the actual position coordinates (position) of the inspection target point on the structure, which is the object of the present invention.

In this embodiment, an operator takes a picture of a planar structure with a camera 1, and the photographed film is developed, converted into a digital image by a film reader 2, and processed in a data processing section 3.

FIG. 2 is a system configuration diagram of the data processing unit 3. In the data processing unit 3, the CPU 31
It comprises an operation unit 31a for performing various processes and a main storage unit 31b. Various peripheral devices are connected to the CPU 31. First, the above-described film reader 2 and external storage device 32 are connected via a data bus. The external storage device 32 sets a program storage area 32a and a data storage area 32b to be stored on a magnetic disk M, which is a removable storage medium, a program for executing an analysis process, and intermediate data generated during the process. And data such as result data. From the film reader 2, digitized appearance image data of the planar structure is transferred.

A display device 33 is connected to the CPU 31. The display device 33 includes three display areas, that is, a low-resolution image area 33a, a fine image area 33b, and a message area 33c. C
The PU 31 also has a mouse 34 and a keyboard 35.
Are connected to enable data input and numerical data input on an image.

In the data processing section 3 having such a configuration, the calculation section 31a sequentially reads the analysis program stored in the program storage area 32a into the main storage section 31b and executes it. Intermediate data in the process of processing is stored in the main storage unit 31b or the data storage area 32b as needed. Mouse 34 or keyboard 35 for linking the pointer
Is operated by the operator, and an input is appropriately performed. The display device 33 displays the image transferred from the film reader 2 in the low-resolution image area 33a and the fine image area 33b, assists in data input, and displays the actual position coordinates of the inspection target point obtained as a result of the processing. , In the message area 33c. Further, an instruction message to the operator can be displayed in the message area 33c, and the operation can be performed interactively.

As described above, with the input operation of the operator,
By executing the sequential data processing, it is possible to execute the analysis processing for obtaining the actual size position coordinates.

In this embodiment, an analog camera and a film reader are used to acquire an image of a planar structure. Instead of these devices, a digital camera is used to directly digitize the image. Is also good.

FIG. 3 is a conceptual diagram of an inspection point position acquisition method using the inspection point position acquisition device of this embodiment. Hereinafter, the concept of the present invention will be described with reference to FIG.

<Indicator setting work for setting reference point> A checkerboard index as shown in this figure is set near four corners of the surface of the planar structure. The reason why such a checkered pattern is used is that the center point is easily recognized by the design. These center points serve as reference points in the actual size coordinate system described below. Instead of the index, four intersections of joints of the planar structure or four branch points of cracks may be determined and used as reference points.

<Measurement of Actual Size Coordinates of Reference Points and Setting of Actual Size Coordinate System> Then, the relative positional relationship between these four reference points is measured. Based on the positional relationship, the surface of the planar structure is regarded as a coordinate plane, an actual size coordinate system (X, Y) is set, and the actual size coordinates of the center points R1, R2, R3, R4 (reference points) of each index are set. (X
i, Yi) (i = 1, 2, 3, 4) is determined in advance. The relative positional relationship of the reference points may be actually measured by the worker on the planar structure, or a method of measuring the three-dimensional coordinates of each reference point by triangulation and projecting them on the planar structure. Is also good. When the intersection of the joints of the planar structure is used as the reference point, the intersection may be obtained from the design drawing.

<Acquisition of Low Resolution Image> Next, the reference point R1
Acquire a digital image (usually all of the plane) of a planar structure containing ＲR4. First, analog photography is performed using the camera 1, and after development, it is converted into a digital image using the film reader 2 (hereinafter, this digital image is referred to as a low-resolution image). In photographing, it is preferable to use a lens with less distortion. When a digital camera is used, a high-resolution camera having as many pixels as possible is used. The same applies to the acquisition of a fine image described later.

<Acquisition of a Fine Image> While obtaining a low-resolution image, a fine digital image of the cracked portion A is acquired. This is a process that has been conventionally performed, and an image in a relatively narrow area near a crack is acquired at a higher resolution than a low-resolution image (hereinafter, this digital image is referred to as a fine image). As in the case of the low resolution image, the fine image is read and acquired by using the film reader 2 to read the developed photographic film, and stored in the computer.

<Measurement of low-resolution image coordinates of reference point> Next, the coordinates of the reference points R1 to R4 in the range of the low-resolution image will be described.
(xi, yi) (i = 1, 2, 3, 4) is obtained. The coordinates in the range of the low-resolution image are expressed by pixel coordinates (hereinafter, referred to as a low-resolution image coordinate system).

<Calculation of First Projection Conversion Coefficient h> Next, the first projection conversion coefficient h is calculated from the actual size coordinates of the reference point and the low resolution image coordinates.

The first projective transformation coefficient h is a coordinate transformation coefficient when the camera 1 is approximately regarded as a pinhole camera on an ideal plane having no irregularities, and has a low-resolution image coordinate system (x, y) and the actual coordinate system (X, Y) are represented by Equation 1, and are a set of coefficients h1, h2,..., h8.

[0046]

X = (h1x + h2y + h3) / (h7x + h8y + 1) Y = (h4x + h5y + h6) / (h7x + h8y + 1) The first projective transformation coefficient h is the reference point R1-4. Actual coordinates (xi, y
i) (i = 1,2,3,4) and low resolution image coordinates (xxi, yyi) (i =
1,2,3,4) is substituted into Equation 1 to form an eight-dimensional linear simultaneous equation, which can be obtained by solving the equation.

<Calculation of Second Projection Transform Coefficient H>
As with the projective transformation coefficient h, the coordinate system
The coordinate transformation from (xx, yy) (hereinafter, referred to as a fine image coordinate system) to the low-resolution image quality image coordinate system (x, y) can also be represented using a projective transformation coefficient.

That is, the second projective transformation coefficient H (H1, H2,...,
H8) is a projective transformation coefficient that gives the transformation of Equation 2.

[0049]

X = (H1xx + H2yy + H3) / (H7xx + H8yy + 1) y = (H4xx + H5yy + H6) / (H7xx + H8yy + 1) The second projective transformation coefficient H is also theoretically As in the method of calculating the projective transformation coefficient h, it can be obtained by using the coordinate information of four reference points. However, since a fine image does not always include four indices, In the embodiment, the second projective transformation coefficient H is obtained by using a non-linear optimization technique called an LM method (Levenberg-Marquardt method) described later.

<Synthesis of Projective Transformation Coefficients> The first projective transformation coefficient h and the second projective transformation coefficient H, which have already been obtained, are combined to convert the fine image coordinate system (xx, yy) to the actual size coordinate system (X, yy). Calculate the composite projective transformation coefficient HH to Y). Since all of these projective transformation coefficients are composed of eight coefficients, they can be used to perform transformation including the elements of rotation, translation, scale, and inclination in the depth direction.

<Designation of Object> In this embodiment, an object is an inspection target point at which actual size coordinates are determined, and is designated by an operator within the range of a fine image.

Normally, before this stage, an analysis and inspection is performed by using another technique such as crack photo analysis, and when the actual coordinates of a certain portion of the structure are required, the process proceeds to the subsequent stages. . The fine image coordinates of the object Pobj specified here are Pobj (xxobj, yyobj).

<Calculation of Actual Size Coordinates of Object> Finally, the fine image coordinates (xxobj, yyobj) of the object Pobj are coordinate-transformed by the projection transformation coefficient HH, and the actual size coordinates (Xobj, Yobj) of the object Pobj, that is, the planar structure Calculate the position on the object.

The concept of the present invention has been described above. In the present invention, the actual size coordinates (position) of an object specified by using a projective transformation coefficient are obtained stepwise. However, the present invention is not limited to the two stages, and the actual size coordinates can be similarly obtained by performing three or more stages of conversion.

Next, the operation of obtaining the actual coordinates of the inspection target point in the first embodiment of the inspection point position obtaining apparatus of the present invention will be described.

FIG. 4 is a flowchart of an analysis program executed in the data processing section 3 to obtain the first projective transformation coefficient h.

First, the actual coordinates (Xi, Yi) (i = 1, 2, 3, 4) of the previously measured reference points R1 to R4 are numerically input from the keyboard 35 (S41). Next, on the image displayed on the low resolution image display section 33a of the display device 33, the mouse 34
The pointer is moved by clicking and the reference points R1 to R1 are clicked.
4 is designated (S42). The reference point R1 is calculated by the arithmetic unit 31a.
The low-resolution image coordinates (xi, yi) (i = 1, 2, 3, 4) are calculated (S43). The arithmetic unit 31a executes an operation based on the solution of the eight-dimensional linear simultaneous equation to calculate a first projective transformation coefficient h, and stores the data in the magnetic disk M mounted on the main storage unit 31b and the external storage device 32. It is stored in the area 32b (S44). That is, in the data processing unit 3, 4
The first projective transformation coefficient h can be obtained by calculating the relationship between the actual size coordinates of the reference point of the point and the low-resolution image coordinates.

Next, an analysis program for obtaining the second projective transformation coefficient H will be described. Prior to execution of this analysis program, the operator operates the low-resolution image area 33a and the fine image area 33 of the display device 33.
Looking at the low-resolution image and the fine image displayed in b, two feature points included in both images are arbitrarily selected.

FIG. 5 is a schematic diagram of an image displayed on the display device 33 when the feature points P1 and P2 are designated in both images. As shown in this figure, a characteristic shape portion such as a branch point of a crack may be set as a characteristic point.

FIG. 6 is a flowchart of an analysis program executed in the data processing unit 3 to obtain the second projective transformation coefficient H.

First, the operator operates the pointer with the mouse 34 to designate feature points P1 and P2 on the low-resolution image as shown in FIG. 5 (S61). Since these feature points merely provide an initial value of the optimization calculation, it is not necessary to accurately grasp the shape. Next, the calculation unit 31a of the data processing unit 3 calculates the low-resolution image coordinates of P1 and P2.
(xp1, yp1), (xp2, yp2) are calculated (S62). And
The operator also specifies feature points P1 and P2 in the fine image (S63). The calculating unit 31a calculates the fine image coordinates of P1 and P2.
(xxp1, yyp1), (xxp2, yyp2) are calculated (S64).

Next, the initial value H0 required for the optimization calculation
Is calculated (S65).

In the LM method, before executing the analysis calculation, the second
It is necessary to give the initial value H0 of the projective transformation coefficient H. This initial value H0 may include some error.

In this embodiment, the conversion from the fine image coordinates to the low-resolution image coordinates is approximately regarded as a Helmert transform (a type of projective transformation, and is performed only by rotation, translation, and scale transformation). , The unknown coefficient of the initial value H0 is reduced from 8 to 4.

[0065]

## EQU3 ## H1 = H5, H2 = -H4, H7 = 0, H8 = 0 Further, a quaternary linear system obtained by substituting the low-resolution image coordinates and the fine image coordinates of the feature points P1 and P2 into Equation 2 The arithmetic unit 31a executes an operation to solve the equation, thereby calculating an initial value H0 of the projective transformation coefficient H.

When the approximate scale ratio S between the low-resolution image and the fine image is known and there is almost no rotation between the two, the following restriction can be further applied.

[0067]

H1 = S, H2 = 0 As a result, the unknown coefficient of [Equation 2] is reduced from 4 to 2, and
It is only necessary to solve the original linear simultaneous equations. At this time, the operator needs only the low-resolution image coordinates and the fine image coordinates of only one feature point.

Next, based on the initial value H0, the arithmetic unit 31a executes the non-linear optimization by the LM method, obtains the final value of the second projective transformation coefficient H, and saves this data (S6).
6).

That is, in this step, the calculation unit 31a performs an optimization calculation so as to minimize the next evaluation function F (H) to obtain a convergence value (final value) of the second projective transformation coefficient H.

[0070]

(Equation 5) Where N is the total number of pixels in the detail image, I (x, y) is the luminance of the pixel at coordinates (x, y) in the low-resolution image, and II (x, y) is the pixel at coordinates (xx, yy) in the detail image. Luminance.

As described above, in the image before and after the projective transformation using the assumed projective transform coefficients, the nonlinear optimization operation is performed such that the pixel sum of the luminance difference is minimized.
The second projective transformation coefficient H can be obtained convergently. Further, by giving the initial value H0 of the second projective transformation coefficient H to the optimization calculation processing by regarding the coordinate transformation as a Helmert transformation, the error of optimization is reduced as compared with a case where no initial value is given,
Calculation time can also be reduced.

As described above, the first projective transformation coefficient
When h and the second projective transformation coefficient H are obtained and stored, it means that preparations for acquiring actual size coordinates, which will be described later, are completed.

FIG. 7 is a flowchart of a program for obtaining actual size coordinates, which is executed by the arithmetic unit 31a.

First, the operator specifies the object Pobj in the fine image (S71). This designation is performed by displaying a fine image in the fine image area 33b of the display device 33, moving the pointer with the mouse 34, and clicking. Next, the fine image coordinates (x
xobj, yyobj) is calculated (S72). Then, the second projective transformation coefficient H determined earlier is read out, and the fine image coordinates (xxob
j, yyobj) is converted to low-resolution image coordinates (xobj, yobj)
Is calculated (S73). Further, the low-resolution image coordinates (xobj, yobj) are transformed using the first projective transformation coefficient h to calculate the actual size coordinates (Xobj, Yobj) of the object Pobj (S).
74). Message area 33c of display device 33
Is the calculated actual coordinates of the object Pobj (Xobj, Yob
j) is displayed (S75).

For the designation of the fine image coordinates of the object, various data (crack positions, widths and lengths determined relative to the positions of the cracks, and the widths and lengths determined relative thereto) obtained by a separately prepared crack analysis device or the like are used. Alternatively, it may be calculated from vector data, etc., and input without the intervention of an operator.

As described above, the projective transformation (coordinate transformation) is performed on the fine image coordinates of the designated object in two steps, whereby the actual size coordinates of the object can be obtained. Since the image data and the projection transformation coefficient data are stored, the actual coordinates can be calculated for different objects any number of times. As shown in FIG. 3, it is also possible to previously obtain the synthesized projective transformation coefficient HH and directly calculate the actual size coordinates (Xobj, Yobj) from the fine image coordinates (xxobj, yyobj) of the object Pobj. .

<Restriction on the resolution ratio between the fine image and the low-resolution image> If the resolution ratio between the fine image and the low-resolution image is within 10, the second projection conversion coefficient H (H1, H2,. H8)
It is known from experience that when the resolution ratio is 10 or more, the obtained second projective transformation coefficient H 2 contains a relatively large error. In order to reduce the error, an image having an intermediate resolution (medium resolution image) is obtained, and the projective transformation coefficients corresponding to the fine image, the medium resolution image, and the medium resolution image and the low resolution image are accurately determined. Then, by performing coordinate conversion using these projective conversion coefficients, it is possible to obtain accurate actual size coordinates as in the case where the resolution ratio is within 10. In addition, when a plane having a poor surface feature such as a concrete structure is used as the inspection target plane, image processing such as normalization of a histogram is performed before calculation of the initial value of optimization, so that the second projective transformation coefficient H Can be reduced.

Further, in the present embodiment, in order to perform coordinate transformation including elements of rotation, translation, scale and inclination in the depth direction, a projective transformation coefficient composed of eight coefficients is used. The point position acquisition device is not limited to this embodiment.

For example, if it is practically sufficient to express the coordinate transformation between the actual size coordinate system and the low-resolution image coordinate system by the Helmert transformation, the first projective transformation coefficient h is composed of four coefficients. It is also possible to reduce the index provided at four places in the form of the above to two places.

If the coordinate transformation between the fine image coordinate system and the low-resolution image coordinate system is sufficient only by the Helmert transformation, the optimization by the LM method described above may be omitted.

As described above, the inspection point position acquiring method or apparatus of the present invention performs the coordinate conversion stepwise using the coefficients obtained from the reference point and the common imaging point (feature point), thereby obtaining the inspection image. From an arbitrary point (object) of the (narrow area image), the position of the inspection target structure on the entire plane can be obtained.

In addition, the use of the projective transformation coefficient composed of eight coefficients enables the position of the inspection point to be accurately obtained even from an image captured at an oblique angle (an image including a tilt element in the depth direction). In addition, the use of the projective transformation coefficient can also absorb the reading distortion of the film reader, and can perform accurate coordinate transformation.

[0083]

According to the inspection point position acquisition method of the present invention, the coordinate transformation is performed stepwise using the position data of the reference point and the coefficient obtained from the common imaging point, so that the specified inspection area can be arbitrarily selected. Since the position of the inspection target structure in the entire plane can be obtained from the point, an excellent effect in practical use is obtained. Especially when inspecting a large-scale planar structure, the position can be obtained remotely, so that the time and labor required for on-site inspection can be reduced and the time and labor can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of a device configuration of an inspection point position acquisition device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a data processing unit of the device shown in FIG.

FIG. 3 is a conceptual diagram of an inspection point position acquisition method according to the present invention.

FIG. 4 is a flowchart of a program for obtaining a first projective transformation coefficient in the apparatus shown in FIG. 1;

FIG. 5 is a schematic diagram of a display image when a feature point is designated in the apparatus shown in FIG. 1;

FIG. 6 is a flowchart of a program for obtaining a second projective transformation coefficient in the apparatus shown in FIG. 1;

FIG. 7 is a flowchart of a program for obtaining actual size coordinates of an object in the apparatus shown in FIG. 1;

[Explanation of symbols]

 Reference Signs List 1 camera 2 film reader 3 data processing unit 31 CPU 31a calculation unit 31b main storage unit 32 external storage device 32a program storage area 32b data storage area 33 display device 33a low resolution image area 33b detail image area 33c message area 34 mouse 35 keyboard

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masayoshi Obata 4-2-18 Shinjuku, Shinjuku, Shinjuku-ku, Tokyo Shinjuku Kofu Building Inside Asia Air Survey Co., Ltd. (72) Inventor Ken Ken Doihara 4-2, Shinjuku, Shinjuku-ku, Tokyo 18 Shinjuku Kofu Building Asia Air Survey Co., Ltd. EE05 GG08 HH24 HH27 KK27 KK37 KZ42

Claims (5)

[Claims] 1. An inspection point position obtaining method for obtaining a position on an arbitrary point of an inspection area included in a plane of an inspection target structure on the plane, the method comprising: reading an inspection image in which the inspection area is imaged; Reading a planar image in which the plurality of reference points and the inspection region determined in advance on the plane are captured; setting the position data of the plurality of reference points measured in advance; and Recognizing the coordinates of a plurality of reference points, based on the recognized coordinates and the set position data, calculating a coefficient for converting any coordinate of the planar image to a position on the plane, A coefficient for converting arbitrary coordinates of the inspection image into coordinates of the plane image is calculated based on a plurality of common imaging points common to the inspection image and the plane image. When an arbitrary point is specified in the range of the inspection image, the coordinates of the inspection image at the specified arbitrary point are converted into a coefficient for converting into coordinates of the plane image and a position on the plane. Converting the position of the inspection target structure into a position on a plane using a coefficient for performing the inspection. 2. An inspection point position acquisition device for determining a position on an arbitrary point of an inspection area included in a plane of an inspection target structure on the plane, wherein an inspection image reading apparatus reads an inspection image obtained by capturing the inspection area. Means, a plurality of reference points predetermined on the plane and a plane image reading means for reading a plane image of the inspection area, and a reference point for setting position data of the plurality of reference points measured in advance. Setting means for recognizing coordinates of the plurality of reference points in the plane image, and converting arbitrary coordinates of the plane image to positions in the plane based on the recognized coordinates and the set position data. Position conversion coefficient calculating means for calculating a coefficient for calculating the coordinates of the inspection image and the plane image based on a plurality of common imaging points common to the plane image. Coordinate conversion coefficient calculating means for calculating a coefficient for converting into coordinates, and when an arbitrary point is specified in the range of the inspection image, the coordinates of the inspection image at the specified arbitrary point are converted to the coordinates of the plane image. Using a coefficient for converting to coordinates and a coefficient for converting to a position on the plane, converting means for converting to a position on the plane of the structure to be inspected; apparatus. 3. The plane image reading means reads a plane image in which four reference points predetermined so as to surround the inspection area are imaged, and the reference point setting means reads the four points measured in advance. Setting the position data of the reference point of the position, the position conversion coefficient calculating means recognizes the coordinates of the four reference points in the plane image, and based on the recognized coordinates and the set position data. 3. The inspection point position acquiring apparatus according to claim 2, wherein a projective transformation coefficient composed of eight coefficients for transforming arbitrary coordinates of the plane image into a position on the plane is calculated. 4. The inspection point position acquiring apparatus according to claim 2, wherein said coordinate transformation coefficient calculating means calculates a projective transformation coefficient composed of eight coefficients. 5. The inspection point position acquiring apparatus according to claim 4, wherein said coordinate transformation coefficient calculating means calculates said projective transformation coefficient by image processing using a non-linear optimization technique.